As shown in FIG. 1, a string-pulling gear 10 of the prior art stringing machine comprises a rotatable wheel 11, a first string-holding member 12, a second string-holding member 13, a tension rod 16, and a weight 17. The rotatable wheel 11 is rotatably mounted to the body of the stringing machine. The first and the second string-holding members 12 and 13 are provided respectively on the circumferential surface thereof with a string groove 14. Both the first and the second string-holding members 12 and 13 are pivoted to one end of the rotatable wheel 11 such that the arresting faces 15 of the first and the second string-holding members 12 and 13 are spaced at a predetermined interval and are opposite to each other. The tension rod 16 is fastened at one end thereof to the rotatable wheel 11. The weight 17 is fitted over the tension rod 16 so that the tension rod 16 is provided with the needed force of gravity acting thereon.
In operation, a game racket frame to be strung is held securely on the machine body in such a manner that a string 18 is put through a string hole of the game racket frame before the string 18 is wound in the string grooves 14 of the first and the second string-holding members 12 and 13. Thereafter, the string 18 is put between the arresting faces 15 of the first and the second string-holding members 12 and 13, as shown in FIG. 2. The string 18 can be tightened up by swiveling the tension rod 16. As soon as the rotatable wheel 11 begins turning, the first and the second string-holding members 12 and 13 are acted on by a force of counteraction by the string 18 so that the first and the second string-holding members 12 and 13 bring about respectively an angular displacement relative to the rotatable wheel 11, as shown in FIG. 3. Such angular displacement persists until such time when the string 18 is held securely by the two arresting faces 15 of the first and the second string-holding members 12 and 13. As soon as the angular displacements of the first and the second string-holding members 12 and 13 cease, the first and the second string-holding members 12 and 13 can rotate synchronously along with the rotatable wheel 11 so as to ensure that the string 18 is tightened with certainty.
The prior art stringing machine described above has shortcomings, which are elucidated hereinafter.
The string 18 is tightened up by means of the tension rod 16 which is acted on by the gravitational force of the weight 17. The tension rod 16 can exert a specific quantity of tension as required on the string 18 only under the circumstance that the tension rod 16 is caused to swivel to locate within an angular range of 5 degrees over a horizontal line and within another angular range of 5 degrees under the horizontal line, as shown in FIG. 4. Otherwise, the tension rod 16 can exert an erroneous quantity of tension on the string 18. Therefore, the string 18 must be rewound on the string-holding members 12 and 13. As shown in FIG. 5, in the course of rewinding the string 18, the tension rod 16 is caused to swivel in reverse. In the meantime, the first and the second string-holding members 12 and 13 are exerted on by a residual tension force of the string 18. As a result, the string 18 is still held securely by the two arresting faces 15 of the first and the second string-holding members 12 and 13. The operator of the stringing machine is therefore required to use his or her hands to move the arresting faces 15 apart so as to release the string 18. It is apparent that the prior art stringing machine can be often a source of aggravation as far as the machine operator is concerned.
In addition, the prior art stringing machine is so cumbersome that it takes up too much of the floor space and that it can not be easily packed, transported, and stored.